If you cut off the trunk at the ground, I would guess that you have either 2 or 4 trees that came up and grew together. If the wire you referred to goes thru the middle of the tree, that would be a real giveaway of the multiple tree stem idea. 24-30 inches is the biggest single stem I have run into and I cut a lot of hedge and is mostly all I burn this time of year. Hedge sprouts from the ground with multiple stems a lot.
Out here, Kansas use to be a little more "tree challenged" and they planted hedge as living fences (before barbed wire). As I understand it, they ground up the hedge balls into a slurry, ran a one bottom plow or dug a ditch where they wanted their fence, and then dumped a line of the slurry into the furrow and covered it back up. A few years later, their living hedge fence took off. I think it was later they figured out it was easier to cut the hedge as fence posts and string wire between, but hedge posts last decades buried in the ground, and we still use them for that out here. I know farmers and ranchers that have old lines of hedge that they "harvest" posts out of about every 20-30 years and they resprout and grow more posts like this for generations.
Once its dried out, it can get a little harder to cut like someone else said! It can throw sparks and the chain needs to be SHARP.